If two alpha particles (each with two protons and two neutrons) are 0.500 m apart, what is the electric potential energy of the system?

U = 1.84 10⁻²⁷ J

Explanation:

Electric potential energy is

        U = k q₁q₂/ r

in this case the electric charge is

         q = 2 p

         q = 2 1.6 10⁻¹⁹

         q = 3.2 10⁻¹⁹ C

indicate the distance between the charges is 0.500 m

we calculate

         U = 9 10⁹  3.2 10⁻¹⁹  3.2 10⁻¹⁹ /0.500

         U = 1.84 10⁻²⁷ J

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me